Method of positioning a stent

ABSTRACT

The invention relates to a rapid exchange catheter system comprising a exchange member having proximal and distal ends, the distal end of the rigid shaft being integral with the proximal end of the exchange member, such that said shaft is adapted to advance the exchange member distally to a desired location wherein the exchange member is positioned concentrically to a catheter shaft.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.07/859,220, filed Mar. 30, 1992, now abandoned.

FIELD OF THE INVENTION

This invention relates to a rapid exchange catheter system. Moreparticularly, this invention relates to a rapid exchange catheter systemcomprising one or more balloon dilatation catheters and an exchangefacilitator consisting of an elongated exchange member and a rigidshaft.

BACKGROUND OF INVENTION

In the utilization of catheters to diagnose and treat various medicaldisorders, it is very often required that more than one device be usedduring the procedure. Because positioning of the catheter at the desiredlocation may be difficult, time consuming, or critical or pose a highrisk, techniques have been developed that facilitate exchange ofcatheter devices.

The most common technique for catheter exchange employs a very longguidewire called an exchange wire. In this technique the exchange wireis placed within a central lumen of a catheter that has been previouslypositioned within the body. To maintain the desired position, theexchange wire is advanced while the catheter is simultaneouslywithdrawn. Once the catheter is completely out of the body, it isremoved from the exchange wire. A second catheter is then positionedover the exchange wire, and, once the catheter is completely on theexchange wire, it is then advanced to the desired site in the body. Thisover-the-wire technique for catheter exchange is considerably timeconsuming, and it requires at least two operators to effect theexchange. In addition, the very long exchange wire extends beyond thesterile field, which adds to the risk of contamination during theprocedure.

U.S. Pat. No. 4,762,129 to Bonzel and U.S. Pat. No. 5,040,548 to Yockdescribe balloon angioplasty catheters that can be exchanged over astandard length guidewire. These catheters are called monorailcatheters, and they are designed such that only a relatively shortsegment of the distal end of the catheter is advanced over theguidewire, i.e., the catheter has a lumen to receive the guidewire thatextends from the distal tip of the catheter to a location proximal tothe balloon. Since the length of the guidewire used is only about halfthat of an exchange wire, the catheter exchange can be done morequickly, and a single operator may do the exchange. However, since amuch shorter segment of the catheter is concentric to the guidewire, themonorail-type catheters have diminished axial support for tracking theguidewire (trackability) and transmission of axial or longitudinalforces (pushability).

In addition to the drawbacks cited above, both of the catheter exchangetechniques described above have two additional shortcomings--increaseddiameter of the catheters to accommodate the guidewire, and risk ofvessel trauma resulting from repeated catheter passages. In a number ofapplications, over-the-wire catheters are too large to be placed at thedesired location. In these applications, smaller catheters, whosediameters have been reduced by eliminating the guidewire lumen, havebeen required. Exchange with these prior art systems consistedessentially of starting over after the first catheter was removed. Thisis often time consuming, and there is an increased risk of complicationsresulting from vessel trauma. U.S. Pat. Nos. 4,944,740 and 4,976,689addressed the trauma issue by providing an outer tubular sheathconcentric to an inner catheter. However, this system would have verylimited application in small blood vessels, as the system itself wouldocclude the blood vessel and cause ischemic complications. Moreover, theouter tubular sheath must be used as a system with its inner catheter;if another catheter or guidewire was used initially, this system couldnot make the exchange.

OBJECTS OF THE INVENTION

It is an object of this invention to provide an atraumatic rapidexchange catheter system.

It is also an object of this invention to provide a rapid exchangecatheter system comprising an exchange member and a pushing shaft.

It is a further object of this invention to provide a rapid exchangecatheter system comprising an exchange member, a pushing shaft, anexpandable sheath membrane, and a hemostasic manifold.

It is a yet further object of this invention to provide a method for therapid exchange of exchange members, such as catheters, guidewires andother devices.

These and other objects of the invention will become more apparent inthe discussion below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 each represent lateral, longitudinal views of respectiveembodiments of the invention;

FIG. 3 represents a cross-sectional view of the embodiment of FIG. 1;

FIGS. 4, 5, and 6 represent additional cross-sectional views ofembodiments of the invention;

FIG. 7 represents an additional embodiment of the invention with thesheath collapsed;

FIG. 8 represents the embodiment of FIG. 7 with the sheath expanded; and

FIGS. 9 and 10 represent cross-sectional views of a further embodimentof the invention.

DETAILED DESCRIPTION OF THE INVENTION

The rapid exchange catheter system (RECS) of this invention provides avery rapid, atraumatic means of exchanging one balloon dilatationcatheter or other device for another balloon dilatation catheter orother device. The RECS is comprised of (1) a distal exchange member,preferably radiopaque, and (2) a rigid shaft or wire attached to theexchange member. Optionally the RECS may also comprise (3) a membranesheath, which is folded around and attached along the length of therigid shaft, and (4) a hemostatic manifold in fluid connection with themembrane sheath.

The RECS is used by, first, placing the exchange member over theproximal portion of the shaft of a catheter, e.g., a balloon dilatation(PTCA) catheter, or a guidewire or other device, that is to be withdrawnfrom a patient. Then, the exchange member is advanced distally along theshaft until the exchange member is positioned at the target site, i.e.,adjacent to or across a stenosis, by pushing the rigid wire. Thecatheter, guidewire, or other device is withdrawn, and then, if amembrane sheath is present, the sheath is unfolded by flushing throughthe hemostatic manifold.

Now, subsequent PTCA catheters, guidewires, or other devices, forexample, atherectomy catheters, laser catheters, stents, angioscopic orultrasound imaging catheters, infusion catheters, perfusion catheters,or the like, may be passed through the sheath to the target site.

Additional exchanges can be made as desired through the sheath. Sincesuch additional exchanges are made within the sheath, the subsequentcatheters and other devices that are introduced do not rub against theintima of the arteries, as happens with both over-the-wire and monorailexchange techniques. The exchanges with the RECS are rapid andatraumatic, with the possibility of endothelial denudation, plaque, andintimal dissection minimized.

In addition to providing a rapid and atraumatic means for exchangingcatheters and other devices, the RECS of the invention can also be usedfor subselective infusion and perfusion. Subselective infusion ofvarious pharmacological agents directly to a lesion, especially during aprocedure, may reduce complications, minimize systemic side-effects, andimprove the long-term outcome of the procedure. In the event of anabrupt closure during an angioplasty, the RECS can be rapidly deployedto provide coronary perfusion. With the sheath in the collapsed, foldedposition, the distal exchange member can act as a temporary stent,providing passive perfusion. If necessary, blood or an oxygen-bearingfluid could be pumped through the sheath for active perfusion.

With the ability to perfuse, the RECS can provide lifesaving capabilitynot presently available in known exchange systems. Patients can bestabilized, and the requirement of surgical standby for PTCA could bereduced or eliminated. In addition to significantly reducing the cost ofa PTCA procedure, the reduction or elimination of the surgical standbyrequirement would facilitate increasing the number of PTCA proceduresperformed each year.

The invention can perhaps be better understood by making reference tothe drawings. The embodiment of the invention 1 shown in FIG. 1comprises an exchange member 2 and a rigid shaft, or corewire, 3 foradvancing and/or retracting the exchange member 2 to and/or from thetarget area in the vasculature (not shown). The shaft 3 is preferably awire. Exchange member 2 comprises a tubular member here; however,exchange member 2 can be comprised of any structure that defines a lumensuitable for exchange purposes.

Another embodiment of the invention 4 can be seen in FIG. 2, wherein theexchange member is comprised of coil 5. Coil 5, which is preferablyhelically wound, is either continuous with shaft 6, that is, formed fromthe same wire, or is another wire attached to shaft 6, preferably bysolder, glue, a weld, or similar affixation. In an alternate embodiment,coil 5 is butt joined to shaft 3.

FIG. 3 represents a cross-sectional view of exchange member 2, whereinit can be seen that shaft 3 is affixed to the interior surface 7 ofexchange member 2. The distal portion of shaft 3 within exchange member2 preferably extends at least about 25% of the length of exchange member2, more preferably about 50 to 100% of the length of exchange member 2.It is within the scope of the invention that shaft 3 may extend distallyof exchange member 2 and have, preferably, a flexible and/or otherwiseatraumatic tip (not shown).

Shaft 3 may optionally, as shown in FIG. 4, be affixed to the outersurface 8 of exchange member 2, in the same manner as discussed foraffixation to interior surface 7. It is also within the scope of thisinvention that shaft 3 could reside within the wall of exchange member2.

As shown in FIG. 5, exchange member 2 may have a longitudinal slit 10 ofsufficient width to enable the exchange member 2 to "snap" over a PTCAcatheter, guidewire or other device. Preferably the width of slit 10would be from about 1 to 5 mm. Also, as shown in FIG. 6, exchange member2 may be discontinuous to the extent that wall members 11, 12 overlap toprovide an opening of the same function as slit 10.

In a typical application of the invention described above, a PTCAcatheter is in position across or adjacent to a stenosis. The exchangemember 2 is positioned over the proximal end of the PTCA catheteroutside the body, and the exchange member 2 is advanced over the PTCAcatheter shaft to the stenosis. Then, the PTCA catheter is withdrawn,leaving the exchange member 2 across the stenosis, where it can functionas a temporary stent to permit perfusion while additional therapy, forexample, PTCA, atherectomy, insertion of a permanent stent, CABG, or thelike, is planned. Optionally such an exchange can be done after thecatheter/manifold hub of the PTCA catheter has been removed.

A secondary device, for example, a second PTCA catheter, is advancedadjacent to shaft 3, to the lesion. Then, the shaft 3 is movedproximally to cause exchange member 2 to move proximally, eitheradjacent to the target site or entirely from the body.

Rigid shaft 1 may be a conventional guidewire, preferably a springguidewire, as is well known. Typical guidewires are shown in U.S. Pat.Nos. 4,757,827, 4,815,478, 4,813,434, 4,619,274, 4,554,929, 4,545,390,4,538,622, 3,906,938, 3,973,556, and 4,719,924, all of which areincorporated herein by reference. In addition, shaft 3 could be solid orhollow, such as a hypotube, with an open distal end, to facilitate druginfusion. The proximal end of the shaft would then preferably have aLuer hub.

The shaft and exchange member of the invention may each optionally havea lubricous coating or covering, such as any of the known polysiloxaneor TEFLON® materials. Also, either, or both, of the shaft and exchangemember could be made of lubricous material.

The exchange member is, in general, made of medically acceptable metal,for example, stainless steel, or rigid polymer, such as a polyesterselected from the group consisting of polyurethanes,polyethyleneterephthalate, polyethyleneterephthalate glycol, andcopolymers thereof, an olefin such as polyethylene or a copolymerthereof, polyvinylchloride, or the like. The exchange member could alsobe component of a material having properties (e.g., shape, size, orflexibility), that change due to hydration, temperature, or anotherfactor. For example, a shape memory alloy such as Nitinol may be used.

It is within the scope of the invention that the exchange member may bedetachable from the shaft, to leave the exchange member permanently inplace. Such detachability could either be immediate or "on demand",where the shaft and exchange member would be joined in such a way, orwith such a mechanism, that the operator could manipulate the proximalend of the shaft to cause the shaft and exchange member to separate. Inthe alternative, the shaft and exchange member may be affixed byappropriate glue, for example, whose adhesive properties would lessenwith time, hydration, or temperature, such that after 24 to 48 hours theshaft could be detached and withdrawn. For example, the adhesive bondingproperties of a hydrogel adhesive would diminish with hydration.

In the embodiment of the invention shown in FIGS. 7 and 8, the RECS 20comprises a coil 21, preferably a radiopaque coil, and a rigid shaft orpushing wire 22. Positioned eccentrically or concentrically, preferablyeccentrically, around shaft 22 is a flexible, collapsible sheath 23,shown collapsed in FIG. 7 and expanded in FIG. 8. At the proximal end ofsheath 23 is a hemostatic manifold 24, including a valved infusion port25 in fluid communication with the interior of sheath 23.

In the alternate embodiment shown in cross-section in FIGS. 9 and 10,sheath 32 is bonded or formed with shaft 30, which defines lumen 31.Pushing wire 33 extends longitudinally within lumen 31.

Sheath 23 or 32 extends distally to at least the distal end of pushingwire 22 or 33. Where exchange member 21 is instead a cylindrical tubularmember, such as exchange member 2, the sheath 23 or 32 can extend intoand/or through said exchange member.

Sheath 23 or 32 facilitates the passage of a second PTCA catheter,guidewire, or other exchangeable device after the first device isremoved, and provides for atraumatic passage of these other devicessince the sheath 23 or 32 prevents contact of the catheter or otherdevice with the lining of the artery. Also, the sheath can provide ameans for subselective catheterization for purposes such as (1) activeperfusion of blood or oxygen-bearing fluid; (2) distal/selective dyeinjection; or (3) selective infusion of medications directly to thelesion site.

The flexible sheath 23 or 32 is preferably bonded by suitable means,such as heat-shrinking or adhesive, to the pushing wire 22 or 33,respectively, either continuously or at discrete points longitudinallyalong the pushing wire 22 or 33. The proximal end of the sheath 23 or 32is bonded by suitable means, such as heat-shrinking or adhesive, to amanifold or hub, and the pushing wire 22 or 33 may terminate at themanifold or hub or extend proximally therethrough. Flexible sheath 23 or32 and/or shaft 30 may each be single or multiple, such as double ortriple, lumen.

The preceding specific embodiments are illustrative of the practice ofthe invention. It is to be understood, however, that other expedientsknown to those skilled in the art or disclosed herein, may be employedwithout departing from the spirit of the invention or the scope of theappended claims.

I claim:
 1. A method of positioning a stent in a corporal channel of apatient's body, which comprises the steps of:(a) advancing into apatient's body through a corporal channel an exchangeable member havingproximal and distal portions to the extent that the distal portion ofsaid exchangeable member is at a desired site inside the patient's bodyand the proximal portion of said first exchangeable member is outsidethe patient's body; (b) outside the patient's body positioning a rapidexchange catheter system comprising(1) an exchange member havingproximal and distal ends and defining a lumen, and (2) a rigid pushingwire having proximal and distal ends, the distal end of the pushing wirebeing integral with and non-detachable from the proximal end of theexchange member, such that said pushing wire is configured to advancethe exchange member distally to a desired location, so that saidexchange member is concentric to the proximal portion of saidexchangeable member and advancing said exchange member distally throughsaid corporal channel to the desired site; and (c) withdrawing saidexchangeable member proximally through said exchange member and removingsaid exchangeable member through said corporal channel from the body,whereby the exchange member functions as a removable stent in thecorporal channel.
 2. A method of positioning a stent in a corporalchannel of a patient's body, which comprises the steps of:(a) advancinginto a patient's body through a corporal channel an exchangeable memberhaving proximal and distal portions to the extent that the distalportion of said exchangeable member is at a desired site inside thepatient's body and the proximal portion of said first exchangeablemember is outside the patient's body; (b) outside the patient's bodypositioning a rapid exchange catheter system comprising(1) an exchangemember having proximal and distal ends and defining a lumen, and (2) arigid pushing wire having proximal and distal ends, the distal end ofthe pushing wire being integral with and non-detachable from theproximal end of the exchange member, such that said pushing wire isconfigured to advance the exchange member distally to a desiredlocation, wherein the pushing wire has a flexible, collapsible sheathhaving proximal and distal ends and being arranged thereon, such that asthe collapsible sheath is expanded by infusion of fluid or insertion ofa catheter, guidewire, or other device, the sheath's diameter increases,and when fluid flow ceases or the catheter, guidewire, or other deviceis withdrawn, the sheath's diameter decreases, so that the exchangemember is concentric to the proximal portion of said exchangeable memberand advancing said exchange member distally through said corporalchannel to the desired site; and (c) withdrawing said exchangeablemember proximally through said exchange member and removing saidexchangeable member through said corporal channel from the body, wherebythe exchange member functions as a removable stent in the corporalchannel.